Production method and device of surface roughened copper plate, and surface roughened copper plate

ABSTRACT

PROBLEMS TO BE SOLVED: To provide a process for roughening both sides of a copper plate by forming a protrusion with a fine bump shape on the both sides of the copper plate, and then to provide a process for a deterioration of an electroplating solution for plating copper to become hard to progress therein. 
     MEANS FOR SOLVING THE PROBLEMS: First of all, there is designed to be arranged electrodes ( 3, 3 ) as a similar pole for therebetween to be opposed to each other in an electroplating copper solution  2 , and then to be arranged a copper plate  4  at therebetween. And then at first there becomes to be performed an anodic treatment for generating a copper fine particles on both surfaces of the copper plate  4 , by performing an electrolytic process with the copper plate  4  as a positive electrode and the electrodes  3  as negative electrodes. And then thereafter there becomes to be performed a cathodic treatment, by performing an electroplating of copper with the copper plate  4  as a negative electrode and the electrodes  3  as positive electrodes, for the copper fine particles to be fixed onto the surfaces of the copper plate  4 . Furthermore, there becomes to be formed the above mentioned protrusion with the fine bump shape thereon, by performing the anodic treatment and then the cathodic treatment as not less than one cycle thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of a prior application Ser. No.12/529,560, filed Apr. 23, 2010, allowed.

TECHNICAL FIELD

The present invention relates to a method of producing a copper platewith a roughened surface used for a metal core of a metal core circuitboard, a device for producing the copper plate with the roughenedsurface, and the copper plate with the roughened surface.

BACKGROUND ART

A metal core circuit board includes a metal plate with good thermalconductivity embedded in an insulating substrate, thereby improving heatuniformity and heat dissipation. The embedded metal plate improves athermal characteristic of the circuit board. Hence, it is possible toflow a larger amount of an electric current even in a similar circuitpattern, thereby reducing a size of a circuit, a peripheral component,or the like.

FIG. 15 is a cross sectional view showing an example of the metal corecircuit board. In the figure, 11 designates an insulating substrate (aprepreg hardened through pressing and heating); 12 designates a metalplate embedded in the insulating substrate 11; 13 designates a circuitpattern formed on a surface of the insulating substrate 11; 14designates a through hole plating; and 15 designates a solder resist.

The metal plate as a core of the metal core circuit board is formed of acopper plate, a copper alloy plate, an aluminum plate, an aluminum alloyplate, or the like, preferably a copper plate in view of thermalconductivity. When the core is formed of the copper plate, the coreselectively has a thickness approximately between 100 μm and 500 μm, sothat the metal core circuit board has sufficient heat uniformity andheat dissipation.

Soldering is performed onto the metal core circuit board with a reflowfurnace or the like in a component mounting process. During the process,it is necessary to prevent an interface between the core metal plate 12and the insulating substrate 11 from being delaminated due to heating.Further, it is necessary to provide the core metal plate and theinsulating substrate with sufficient adhesion and heat resistanceagainst heat generated in use.

In general, a copper foil used as a circuit conductive member of acircuit board is an electrolytic copper foil having a roughened surfaceon one side and a gloss surface on the other side. Normally, theroughened surface is formed through electroplating, and copper platingor the like is performed on the roughened surface to grow a protrusionwith a fine bump shape, thereby producing the electrolytic copper foil.FIG. 16 shows a scanning electron micrograph of the roughened surface ofthe electrolytic copper foil for the circuit board. The copper foilformed through electroplating has a thickness between 35 μm and 70 μm.When the copper foil has a thickness greater than the range, it takes along period of time for plating, thereby increasing cost for a practicaluse. Further, the core of the metal core circuit board needs to have theroughened surface on both sides. In order to use the electrolytic copperfoil as the core metal plate, it is necessary to perform an additionalroughening treatment on the gloss surface thereof, thereby furtherincreasing cost.

In many cases, a large number of holes are formed in the core metalplate of the metal core circuit board for forming through holesconnecting circuit patterns on both surfaces. After performing theroughening treatment on the both surfaces of the copper plate withoutholes, when holes are formed in the copper plate, the roughened surfacesmay be damaged. Further, it is necessary to clean and remove machine oilattached to the copper plate when holes are formed. Accordingly, it isdesirable to perform the roughening treatment on the both surfaces afterforming the holes for the through holes in the copper plate.

In view of the reasons mentioned above, it is difficult to use theelectrolytic copper foil for the core metal plate of the metal corecircuit board.

When a rolled copper plate capable of being produced with a rolling millroll at a relatively low price is used for a copper plate with athickness greater than 100 μm, i.e., a preferred thickness for the coreof the metal core circuit board, it is possible to significantly reducecost. However, the rolled copper plate has smooth surfaces on bothsides. Accordingly, when the rolled copper plate is embedded in aninsulating substrate, it is necessary to perform the rougheningtreatment on both surfaces thereof for enhancing adhesion to theinsulating substrate (a glass epoxy board).

A process for roughening the surface of the copper plate includesetching, a chemical treatment, or the like. A typical example is CZtreatment of MEC COMPANY LTD. In the CZ treatment, a copper etchingparticle and a organic nitrogen compound coating film are formed on thesurface of the copper plate using a oxidation reduction reaction of abivalent copper compound, so that it is possible to obtain a peelingstrength between 0.4 kN/m and 0.8 kN/m according to JIS-C6471. When thepeeling strength in the range is obtained, it is possible to satisfy aminimum requirement for the roughening process for adhering to theinsulating substrate.

There has been known a process for forming a protrusion with a fine bumpshape on a surface of a copper plate through a copper plating process ata high current density such as a copper foil of a printed circuit boardor the like (refer to patent document 1). The protrusion with the finebump shape has an anchoring effect. Accordingly, it is effective forenhancing adhesion to the insulating substrate as opposed to etching,chemical treatment, or the like.

-   Patent Document 1: Japanese Patent Publication No. 2005-008973

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

When a surface of a rolled copper plate is roughened, as compared to anelectrolytic copper foil, it is possible to obtain only a shallowroughened surface through etching, chemical treatment, or the like.Further, as compared to an electrolytic copper foil, the peelingstrength is low, and it is difficult to obtain reliability in heatresistance similar to that of the electrolytic copper foil. Further, inetching, a large quantity of a waste solution is generated correspondingto a number of processes, thereby causing cost and environmental issue.

In the process disclosed in patent document 1, the surface of the foilof copper is roughened through copper plating at a high current density.Accordingly, a copper plating solution tends to be easily deteriorated,and a large amount of the copper plating solution is consumed, therebyincreasing cost.

Further, the electrolytic copper foil is produced through plating in astate that one surface thereof contacts with a drum electrode whilerotating. Hence, only one surface of the copper foil is roughened, andit is necessary to roughen a gloss surface thereof through copperplating. Accordingly, it is difficult to apply the roughening processthrough copper plating on both surfaces of the copper plate.

An object of the present invention is to provide a method of producing acopper plate with a roughened surface, and to provide a device forproducing the copper plate with a roughened surface, in which it ispossible to concurrently roughen both surfaces of a copper plateregardless of holes for through holes without excessively deterioratingan electroplating copper solution.

Means for Solving the Problem

According to the present invention, a method of producing a copper platewith a roughened surface through forming a protrusion in a fine bumpshape on a surface of the copper plate to roughen the surface of thecopper plate, includes the steps of:

arranging electrodes with a same polarity to face each other in anelectroplating copper solution;

arranging the copper plate between the electrodes; and

performing more than one cycle of an anodic treatment and a cathodictreatment to form the protrusion in the fine bump shape. The anodictreatment is performed for forming a copper fine particle on bothsurfaces of the copper plate through an electrolytic process with thecopper plate as a positive electrode and the electrodes as a negativeelectrode. The cathodic treatment is performed after the anodictreatment for fixing the copper fine particle to the surfaces of thecopper plate through a copper electroplating with the copper plate as anegative electrode and the electrodes as a positive electrode.

According to the present invention, in order to adjust a platethickness, the method may further includes the step of performing acopper plating with the copper plate as the negative electrode and theelectrodes as the positive electrode in an electroplating coppersolution before performing the anodic treatment for the first time.

According to the present invention, in the method of producing thecopper plate with the roughened surface, one pair of the electrodes withthe same polarity may be arranged in the electroplating copper solutionto face each other, the copper plate may be arranged between theelectrodes with the same polarity, and more than one cycle of the anodictreatment and the cathodic treatment may be performed without moving thecopper plate relative to the electrodes with the same polarity.

According to the present invention, in the method of producing thecopper plate with the roughened surface, one pair of positive electrodesmay be arranged to face each other in the electroplating coppersolution, one pair of negative electrodes may be arranged to face eachother in the electroplating copper solution in parallel to the positiveelectrodes, and more than one cycle of the anodic treatment and thecathodic treatment may be performed. The anodic treatment is performedwith the copper plate as the positive electrode while the copper plateis arranged between the negative electrodes. The cathodic treatment isperformed with the copper plate as the negative electrode after thecopper plate relatively moves between the positive electrodes.

According to the present invention, in the method producing the copperplate with the roughened surface, one pair of or a plurality of pairs ofpositive electrodes may be arranged to face each other in theelectroplating copper solution, one pair of or a plurality of pairs ofnegative electrodes may be arranged to face each other in theelectroplating copper solution in parallel to the positive electrodes,and the anodic treatment and the cathodic treatment may be performedalternately while the copper plate is sequentially moving from betweenthe electrodes at one end side to between the electrodes at the otherend side.

According to the present invention, in the method of producing thecopper plate with the roughened surface, the anodic treatment and thecathodic treatment may be performed on a combined copper plate formed oftwo copper plates in one sheet. The combined copper plate is separatedinto the copper plates one by one to obtain two copper plates with oneroughened surface.

According to the present invention, in the method of producing thecopper plate with the roughened surface, the anodic treatment ispreferably performed with an electric current density between 1 A/dm²and 8 A/dm² for three minutes to ten minutes, and the cathodic treatmentis preferably performed with an electric current density between 1 A/dm²and 8 A/dm² for three minutes to ten minutes.

According to the present invention, in the method of producing thecopper plate with the roughened surface, the electroplating coppersolution is preferably maintained at a temperature between 18° C. and32° C., more preferably between 24° C. and 30° C.

Further, the method of producing the copper plate with the roughenedsurface preferably further includes the step of forming a predeterminedhole in the copper plate at a predetermined position thereof beforeperforming the anodic treatment and the cathodic treatment.

According to the present invention, a device for producing a copperplate with a roughened surface preferably includes an electrolytic bathfor retaining an electroplating copper solution; one pair or a pluralityof pairs of positive electrodes arranged in the electrolytic bath toface each other in a tandem arrangement; one pair or a plurality ofpairs of negative electrodes arranged in the electrolytic bath to faceeach other in a tandem arrangement; a negative electrode bus bararranged horizontally at an upper side between the one pair or theplurality of pairs of the positive electrodes for hanging the copperplate; a positive electrode bus bar arranged horizontally at an upperside between the one pair or the plurality of pairs of the negativeelectrodes for hanging the copper plate; and an insulating bar forconnecting the negative electrode bus bar and the positive electrode busbar.

According to the present invention, a device for producing a copperplate with a roughened surface preferably includes an electrolytic bathfor retaining an electroplating copper solution; one pair or a pluralityof pairs of positive electrodes and one pair or a plurality of pairs ofnegative electrodes alternately arranged in the electrolytic bath toface each other in a tandem arrangement; a negative electrode bus bararranged horizontally at an upper side between the one pair or theplurality of pairs of the positive electrodes for hanging the copperplate; a positive electrode bus bar arranged horizontally at an upperside between the one pair or the plurality of pairs of the negativeelectrodes for hanging the copper plate; and an insulating bar forconnecting the negative electrode bus bar and the positive electrode busbar.

According to the present invention, a copper plate with a roughenedsurface has a predetermined hole formed at a predetermined positionthereof. A surface of the copper plate includes a protrusion with a finebump shape having a grain size not larger than 10 μm, and a surfaceroughness Rz between 3 μm and 20 μm. In this case, the hole preferablyincludes a roughened inner face, and the protrusion with the fine bumpshape on the inner face of the hole preferably has a height not higherthan 20 μm.

Effects of the Invention

According to the present invention, the anodic treatment is performedfor generating copper fine particles on both surfaces of the copperplate through the electrolytic process with the copper plate as thepositive electrode and the electrodes as the negative electrode.Afterward, the cathodic treatment is performed for fixing the finecopper particles to the surfaces of the copper plate through the copperplating with the copper plate as the negative electrode and theelectrodes as the positive electrode. Accordingly, it is possible toform the protrusion with the fine bump shape on both surfaces of thecopper plate, thereby roughening both surfaces of the copper plate. Theanodic treatment and the cathodic treatment are performed in the sameelectroplating copper solution. Accordingly, the copper plate suppliescopper ions during the anodic treatment, and the copper ions in thesolution are consumed during the cathodic treatment. When values ofelectric currents are set close to each other during the anodictreatment and the cathodic treatment, a variation in a concentration ofthe copper ions in the processing solvent becomes very small. Hence, theelectroplating copper solution tends not to be deteriorated easily,thereby making it possible to use the electroplating copper solutionover a long period of time. As a result, it is possible to reduce aconsumed quantity of the electroplating copper solution, therebyreducing cost. It is desirable that the values of the electric currentsduring the anodic treatment and the cathodic treatment are the same.Even when there is a difference, it is possible to suppress consumptionof the copper ions as opposed to ordinary copper plating. Further, it ispossible to roughen both surfaces of the copper plate and the innerfaces of the holes for the through holes at the same time. Accordingly,it is possible to easily obtain the copper plate with the roughenedsurface suitable for a metal core of a metal core circuit board.

Before performing the anodic treatment for the first time, when thecopper plating is performed with the copper plate as the negativeelectrode and the electrodes as the positive electrode, it is possibleto easily form the protrusion with the fine bump shape, and to adjustthe thickness of the copper plate as well.

After the anodic treatment and the cathodic treatment are performed onthe combined copper plate formed of the two copper sheets combined inthe one sheet, when the combined copper plate is separated into thecopper plates one by one, it is possible to obtain the two copper plateswith one roughened surface. In the copper plate thus obtained, anopposite surface of the roughened surface is not roughened to a largeextent and remains smooth.

According to the present invention, in addition to the plating processof the present invention, the device of producing the plate isapplicable to other types of plating processes such as a horizontalline, a vertical line, a pusher line, or the like, as far as the processsatisfies a basic principle of the plating process of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

FIG. 1 shows one embodiment according to the present invention. In thefigure, 1 designates an electrolytic bath, 2 designates anelectroplating solution for plating copper retained in the electrolyticbath 1, 3 designates a pair of electrodes with a same polarity arrangedin the electroplating copper solution 2 to face each other, 4 designatesa copper plate with a surface thereof to be roughened arranged atbetween the electrodes 3, 5 designates a frame body for holding thecopper plate 4, 6 designates a hanger metal fitting, and 7 designates abus bar for maintaining the copper plate 4 as a positive electrode or anegative electrode via the hanger metal fitting 6 and the frame body 5.An electrical wiring for maintaining the electrodes 3 at a polarityopposite to that of the copper plate 4 is not shown in the figure

The electrodes 3 are formed of a copper plate or a copper bar. It ispossible to use an insoluble electrode available in market as well (anoxide based insoluble electrode with titanium as a base material, aplatinum based insoluble electrode or the like). The electrode normallyhas a facing area similar to one surface of the copper plate to beroughened. It may be possible to increase or decrease the area, or todivide the electrode into a plurality of sheets according tocircumstances. The electroplating copper solution 2 is an electroplatingsolution for plating copper available in market. The electroplatingcopper solution 2 has a composition of, for example: copper sulfatebetween 40 g/l and 250 g/l; sulfuric acid between 30 g/l and 210 g/l;hydrochloric acid between 10 ppm and 80 ppm; and an additive agent suchas a brightening agent or the like in a quantity specified by a maker(as approximately between 2 ml/l and 10 ml/l). The electroplating coppersolution 2 is agitated by a pneumatic agitating unit (bubbling) arrangedat a bottom part of the electrolytic bath 1, a jet nozzle arrangedbetween the electrode in the bath 1 and the copper plate with thesurface to be roughened, or the like (not shown).

In the device with the configuration mentioned above, first, an anodictreatment is performed for generating copper fine particles on bothsurfaces of the copper plate 4 in a quantity required for forming aprotrusion with a fine bump shape thereon through an electrolyticprocess with the copper plate 4 as a positive electrode and theelectrodes 3 as negative electrodes. Next, the polarity is reversed, anda cathodic treatment is performed for fixing the copper fine particlesto the surfaces of the copper plate 4 through an electroplating with thecopper plate 4 as a negative electrode and the electrodes 3 as positiveelectrodes. Through the anodic treatment and the cathodic treatment, itis possible to form the protrusion with the fine bump shape onto thesurfaces of the copper plate, that is superior in adhesive property toan insulating substrate, similar to the protrusion with the fine bumpshape on the surfaces of the conventional electrolytic copper foil.After the cathodic treatment, the copper plate with the roughenedsurface is moved outside the electrolytic bath 1, and a washing processis performed in clear water. As required, an after treatment such as anacid cleaning process, a washing water process, a rust preventionprocess or the like is performed. The after treatment is similar to anafter treatment performed in the normal copper electroplating process.

The copper fine particles generated in the anodic treatment are socalled an anode slime, i.e., an unnecessary substance in the copperelectroplating, and are considered to be generated when copper, copperoxide, copper ions, or the like at a high concentration remains on thesurface of the copper plate due to a difference between a precipitationrate of the copper ions from the copper plate and a diffusion rate ofthe ions into the plating solution in the anodic treatment. In thepresent invention, the anode slime is utilized for forming theprotrusion with the fine bump shape. When the copper fine particles aregenerated in a large amount, the copper fine particles tend to move awayfrom the surface of the copper plate, thereby making it difficult toform the protrusion with the fine bump shape thereon. When the copperfine particles are generated in a small amount, it is difficult to formthe protrusion with the fine bump shape. A condition of the anodictreatment may vary for forming the copper fine particles in a necessaryquantity to form the protrusion with the fine bump shape on the surfaceof the copper plate according to a density of an electric current, aprocessing time, a solution temperature, or the like, and it isdetermined experimentally. According to the experiment, preferredconditions of the anodic treatment are the electric current densitybetween 1 A/dm² and 8 A/dm², the solution temperature between 18° C. and32° C., and the processing time between three minutes and ten minutes. Acondition of the cathodic treatment for fixing the copper fine particlesto the surfaces of the copper plate is determined experimentally aswell. According to the experiment, preferred conditions of the cathodictreatment are the electric current density between 1 A/dm² and 8 A/dm²,the solution temperature between 18° C. and 32° C., and the processingtime between three minutes and ten minutes. The conditions areapproximately similar to conditions of the ordinary copperelectroplating.

An important point of the present invention is that the protrusion withthe fine bump shape is formed not by performing the copperelectroplating at a higher electric current density such as the processfor roughening the surface of the electrolytic copper foil, but byperforming the process for generating the copper fine particles and thenby performing the process for fixing the same thereon under theconditions of the ordinary copper electroplating. According to theprocesses, the similar individual processes of the anodic treatment andthe cathodic treatment are performed in the electroplating coppersolution. Accordingly, it is possible to reduce a consumption of thecopper ions. Hence, the electroplating copper solution is lessdeteriorated, and it is possible to use the plating solution for a longperiod of time. As a result, it becomes able to reduce the quantity ofthe plating solution to be consumed.

It is possible to roughen the surface of the copper plate by performingthe individual processes of the anodic treatment and then the cathodictreatment in only one cycle. When it is required to obtain high heatresistance, it is desirable to perform the processes more than twocycles. The copper electroplating may be performed in the same devicebefore the anodic treatment for the first time. The copperelectroplating is effective for forming the protrusion with the finebump shape, or adjusting a thickness of the copper plate.

Similar to the method described above, after the anodic treatment andthe cathodic treatment are performed on a copper plate combined of twocopper plates, the combined copper plate may be separated into thecopper plates one by one. Accordingly, it is possible to obtain the twocopper plates with roughened one surface (similar for the embodimentsdescribed below). When the copper plates are obtained in such a manner,a backside surface of the roughened surface is not roughened.Accordingly, it is possible to maintain the backside surface smooth.

Second Embodiment

FIG. 2 shows another embodiment according to the present invention. InFIG. 2, a similar symbol is used for a part similar to that in FIG. 1.In the embodiment, different from the first embodiment, the electrolyticbath 1 is extended, and one pair of positive electrodes 3 a facing eachother and one pair of negative electrodes 3 c facing each other arearranged in a tandem arrangement in the electroplating copper solution2. A negative electrode bus bar 7 c is arranged horizontally at an upperside between the pair of the positive electrodes 3 a. A positiveelectrode bus bar 7 a is arranged horizontally at an upper side betweenthe one pair of the negative electrodes 3 c. The negative electrode busbar 7 c and the positive electrode bus bar 7 a are connected in a linearform via an insulating bar 8. The negative electrodes 3 c are made of acopper plate or a copper bar. The positive electrodes 3 a are formed ofa copper plate or a copper bar, and are preferably formed of aninsoluble electrode (an oxide based insoluble electrode with titanium asa base material, a platinum based insoluble electrode, or the like). Theelectrode normally has a facing area similar to one surface of thecopper plate to be roughened. It may be possible to increase or decreasethe area, or to divide the electrode into a plurality of sheetsaccording to circumstances.

When the copper plate with the roughened surface is produced with thedevice, the copper plate 4 is hung on the positive electrode bus bar 7 aand arranged between the negative electrodes 3 c as shown in FIGS. 2(A)and (B), and the anodic treatment is performed with the copper plate 4as the positive electrode. Accordingly, the copper fine particles areformed with a sufficient quantity for forming the protrusion with thefine bump shape on both of the surfaces of the copper plate 4. After theanodic treatment, the hanger metal fitting 6 is moved from the positiveelectrode bus bar 7 a over the insulating bar 8 to the negativeelectrode bus bar 7 c, so that the copper plate 4 is arranged betweenthe positive electrodes 3 a. In this state, the cathodic treatment isperformed with the copper plate 4 as the negative electrode. During thecathodic treatment (copper plating), the copper fine particles are fixedonto the copper plate, and the protrusion with the fine bump shape areformed onto the surfaces of the copper plate. After the cathodictreatment, the copper plate with the roughened surface is moved outsidethe electrolytic bath 1, and a washing process is performed in clearwater. As required, an after treatment such as an acid cleaning process,a washing water process, a rust prevention process or the like isperformed. The after treatment is similar to an after treatmentperformed in the normal copper electroplating process.

The anodic treatment and the cathodic treatment may be performed in onlyone cycle, and it is desirable to perform the processes more than twocycles. When the processes are performed than the two cycles, after thecathodic treatment in the previous cycle, the copper plate is moved backbetween the negative electrodes 3 c and the anodic treatment isperformed. When the processes are performed than the two cycles, thecathodic treatment is performed in the end. Before the anodic treatmentat the first time, the copper plate may be arranged between the negativeelectrodes to perform the copper electroplating.

When the anodic treatment and the cathodic treatment are performed inone cycle, it possible to perform the anodic treatment and the cathodictreatment at the same time by arranging a next copper plate to beroughened between the negative electrodes 3 c when the copper plate ismoved between the positive electrodes 3 a as shown in FIGS. 2(C) and (D)to perform the cathodic treatment after the anodic treatment.Accordingly, it is possible to increase production efficiency of thecopper plate with the roughened surface two times as opposed to thefirst embodiment.

Third Embodiment

FIG. 3 shows a further embodiment according to the present invention. InFIG. 3, a similar symbol is used for a part similar to that in FIG. 2.In the embodiment, the electrolytic bath 1 is extended approximately twotimes that of the device shown in FIG. 2 for performing the anodictreatment and the cathodic treatment of the copper plate two cycles.Further, one pair of positive electrodes 3 a facing each other and onepair of negative electrodes 3 c facing each other are arrangedalternately in a tandem arrangement in the electroplating coppersolution 2. Further, the negative electrode bus bar 7 c is arrangedhorizontally at the upper side between the one pair of the positiveelectrodes 3 a, and the positive electrode bus bar 7 a is arrangedhorizontally at the upper side between the one pair of the negativeelectrodes 3 c. The negative electrode bus bar 7 c and the positiveelectrode bus bar 7 a adjacent to each other are connected in a linearform via the insulating bar 8.

For producing the copper plate with the roughened surface with thedevice, the copper plate 4 is moved from between the negative electrodes3 c at one end of the electrolytic bath 1 (at left side in the figure)to between the positive electrodes 3 a at the other end thereof, and theanodic treatment and the cathodic treatment are alternately performed.After the cathodic treatment between the positive electrodes 3 a at theother end, the copper plate with the roughened surface is moved outsidethe electrolytic bath 1, and a washing process is performed in clearwater. As required, an after treatment such as an acid cleaning process,a washing water process, a rust prevention process or the like isperformed. The after treatment is similar to an after treatmentperformed in the normal copper electroplating process. After moving outthe copper plate 4 from between the positive electrodes 3 a at the otherend to outside the electrolytic bath 1, remaining three copper platesare moved to the other end by one pitch. Then, a copper plate to beroughened next is placed between the negative electrodes 3 c at the oneend opened, and the anodic treatment and the cathodic treatment areperformed between all of the electrodes at the same time. Accordingly,it is possible to continuously perform the anodic treatments and thecathodic treatments in two cycles.

The negative electrodes 3 c are made of a copper plate or a copper bar.The positive electrodes 3 a may be formed of a copper plate or a copperbar, and are preferably formed of an insoluble electrode (an oxide basedinsoluble electrode with titanium as a base material, a platinum basedinsoluble electrode, or the like). The electrode normally has a facingarea similar to one surface of the copper plate to be roughened. It maybe possible to increase or decrease the area, or to divide the electrodeinto a plurality of sheets according to circumstances.

When a larger number or a larger quantity of copper plates areprocessed, a cathodic treatment section and an anodic treatment arearranged to have lengths and numbers several times more than the case inaddition to the electrodes facing each other. The copper plates in anumber corresponding to the multiple number are concurrently processedat an increased travelling speed thereof, thereby arbitrarily increasinga processing tact. In this case, a length ratio of the processing bathmay be adjusted according to a required number of the cathodic treatmentand the anodic treatment, a time ratio, or the like. With the device, itis possible to produce the copper plate with the roughened surface withthe tact less than the required time of the cathodic treatment and theanodic treatment.

The anodic treatment and the cathodic treatment may be performed morethan three cycles as required. When performing more than three cycles,more than three sets of one pair of positive electrodes 3 a facing eachother and one pair of negative electrodes 3 c facing each other may bearranged alternately in a tandem arrangement.

(Conditions of the Anodic Treatment)

Conditions of the anodic treatment are determined through an experiment.According to the experiment, for generating the copper fine particles ina quantity sufficient for forming the protrusion with the fine bumpshape on both surfaces of the copper plate, the process is preferablyperformed in an ordinary copper electroplating solution (copper sulfatebetween 40 g/l and 250 g/l, sulfuric acid between 30 g/l and 210 g/l,hydrochloric acid between 10 ppm and 80 ppm, an additive such as abrightening agent or the like in a quantity specified by a maker) withthe electric current density between 1 A/dm² and 8 A/dm² for betweenthree minutes and ten minutes, while maintaining the plating solution ata temperature between 18° C. and 32° C.

Even when the solution temperature and the electric current density arewithin the ranges, if the processing time for the anodic treatment isshorter than three minutes, it is difficult to form the protrusion withthe fine bump shape due to an insufficient quantity of the copper fineparticles formed on the surface of the copper plate. When the processingtime for the anodic treatment is longer than ten minutes, it isdifficult to form the protrusion with the fine bump shape in a preferredway due to an excessive quantity of the copper fine particles formed onthe surface of the copper plate. Hence, it is desirable that theprocessing time for the anodic treatment is between four minutes andeight minutes, more preferably between four minutes and six minutes.

Even when the solution temperature and the processing time are withinthe ranges, if the electric current density is lower than 1 A/dm², it isdifficult to form the protrusion with the fine bump shape due to aninsufficient quantity of the copper fine particles formed on the surfaceof the copper plate. If the electric current density is higher than 8A/dm², it is difficult to form the protrusion with the fine bump shapein a preferred way due to an edge delamination or an excessive quantityof the copper fine particles formed on the surface of the copper plate.Hence, it is desirable that the electric current density of the anodictreatment is between 1 A/dm² and 8 A/dm², more preferably between 1A/dm² and 5 A/dm².

Even when the electric current density and the processing time arewithin the ranges, if the solution temperature is lower than 18° C., itis difficult to form the protrusion with the fine bump shape due to aninsufficient quantity of the copper fine particles formed on the surfaceof the copper plate. When the solution temperature is higher than 32°C., it is difficult to form the protrusion with the fine bump shape in apreferred way due to an excessive quantity of the copper fine particlesformed on the surface of the copper plate.

(Conditions of the Cathodic Treatment)

Conditions of the cathodic treatment are determined through anexperiment as well. The cathodic treatment is performed in the copperplating solution similar to the anodic treatment. Accordingly, asolution temperature is similar to that of the anodic treatment.Moreover, the anodic treatment and the cathodic treatment are performedat the same time. Accordingly, a processing time is desirable to besimilar to that of the anodic treatment. An electric current density ofthe anodic treatment is different from that of the cathodic treatment.The cathodic treatment is preferably performed with the electric currentdensity between 1 A/dm² and 8 A/dm². When the electric current densityis lower than 1 A/dm², it is difficult to fix the protrusion with thefine bump shape on the surface of the copper plate due to aninsufficient copper plating amount. When the electric current density ishigher than 8 A/dm², the protrusion with the fine bump shape tends to becovered with a plated layer due to an excessive copper plating amount,so that it is difficult to form the protrusion with the fine bump shapethereon in a preferred way. Hence, it is desirable that the electriccurrent density of the cathodic treatment is between 1 A/dm² and 8A/dm², more preferably between 1 A/dm² and 5 A/dm².

(Regarding the Protrusion with the Fine Bump Shape)

The protrusion with the bump shape is a precipitated form, in which acopper plate base and a particle or particles are attached through anecking (constricted part). With the necking, an anchoring effect iscreated with respect to a resin of an insulating substrate, therebyincreasing an adhesive strength. The form includes a bump with a clustershape (a bunch shape of grapes) in a size between approximately 1 μm and20 μm, in which particles are connected each other. Further, theprotrusion with the bump shape also includes a mixture of a protrusionwithout a necking and a protrusion with a bump shape, as long as itsatisfies a particle size and a grain size described later. It isdesirable that the grain size of the protrusion with the bump shape isnot larger than 10 μm. In the range, the adherence between theprotrusion and the base of the copper plate is good, thereby obtaining agood strength with the insulating substrate. The grain size of theprotrusion with the fine bump shape is more preferably between 0.5 μmand 3 μm, so that uniformity and the bonding strength between theprotrusion and the base are further improved. A roughness Rz is measuredmacroscopically. The roughness Rz is preferably between 3 μm and 20 μm.In the range, the adherence between the protrusion and the base and thebonding strength with the insulating substrate are good. The roughnessRz thereon is more preferably between 7 μm and 16 μm, so that uniformityand the bonding strength between the protrusion and the base are furtherimproved. Note that it is hard to measure a roughness of an inner faceof a hole. It may be suffice that the inner face of the hole isroughened, as far as the bumps are not overgrown to decrease a diameterof the hole less than specification, or the bumps are not peeled offupon laminating the insulating substrate. A height of the bump (in acase of a cluster shape, an entire height of the cluster is consideredto be the height of the bump) is preferably less than 20 μm. In therange, the diameter of the hole does not decrease, or the bump is notpeeled off.

In the processes described above, an arbitrary jig may be used forholding the copper plate to be roughened. The jig is preferably made ofa metal such as copper, a copper alloy, stainless, titanium, or thelike. The electric current is consumed even on a metal surface of thejig itself. Accordingly, it is necessary to set a value of the electriccurrent necessary for the processes by adding a metal surface area ofthe jig immersed in the solution to a surface area of the plate to beprocessed.

EXAMPLES

The copper plate used in examples is a tough pitch copper rolled platehaving a length of 500 mm, a width of 380 mm, and a thickness of 400 μmor 200 μm. The copper plate with the thickness of 400 μm is processedfor drilling holes for through holes with an inner diameter between 1 mmand 2 mm and a total area of 10% of a plate area (locations of the holesare arbitrary). The copper plate with the thickness of 200 μm isprocessed in an overlapped state of two sheets to obtain the copperplate with roughened one side used for a peel test.

A composition of the electroplating solution for the processes is:copper sulfate 90 g/l; sulfuric acid 180 g/l; and hydrochloric acid 60ppm. As a supplementary agent, a brightening agent and a restrainingagent used for a copper gloss plating in general are used with aquantity specified by a maker. An example of a commercial product of thebrightening agent and the restraining agent includes COPPER GLEAM™brightening agent for a copper sulfate plating produced by Rohm and HaasCompany, KUPPELIGHT™ and PYRONIKKA™ produced by Nihon Kagaku Sangyo Co.,Ltd., or the like. The agents are selected according to a type ofplating bath, a substance for the electrodes, an object to use the finalproduct, or the like.

Example 1

The anodic treatment is performed on the copper plates with thethicknesses of 400 μm and 200 μm at a solution temperature of 28° C. andan electric current density of 4.5 A/dm² for approximately five minutes.Thereafter, the cathodic treatment is performed at the same solutiontemperature and an electric current density of 1.4 A/dm² forapproximately five minutes, thereby producing the copper plate with theroughened surface. A surface of the copper plate with the roughenedsurface is shown in FIG. 4 (a magnification of 3,000 in SEM). It isfound that the grain size of the protrusion with the fine bump shape onthe primary surface is not larger than 3 μm, and the surface is covereduniformly with the protrusion with the fine bump shape. A bump with acluster shape is also found, and a grain size and a height thereof arenot more than 10 μm. The surface roughness is measured with a super deepcolor 3D shape measurement microscope VK-9510 produced by KEYENCECORPORATION, and the surface roughness Rz is 7.5 μm. There is nodifference in the shape of the protrusion with the fine bump shapebetween the copper plate with the thickness of 400 μm and the copperplate with the thickness of 200 μm.

A commercially available adhesive tape with a width of 10 mm is attachedto the copper plate with the roughened surface, and the pulling off testis performed. As a result thereof, the protrusion with the fine bumpshape is not peeled off, and only an adhesive of the adhesive tape ispeeled off from an interface of the adhesive tape, and the adhesive ofthe adhesive tape remains on the copper plate with the roughenedsurface.

Next, ten sheets of commercially available glass epoxy prepreg FR-4 (aninsulating substrate material) with a thickness of 0.1 mm are laminatedon the copper plate with one roughened side with the thickness of 200μm. They are integrated through pressing and heating under a conditionsimilar to that of a hot pressing of an electrolytic copper foil and theFR-4 prepreg, thereby obtaining a laminated plate of the copper plateand the insulating plate. A sample is cut out from the laminated plate,and a peeling strength test is performed according to JIS-C6471 on anactual sample and a sample after soaking into a molten solder at atemperature of 260° C. for sixty seconds. A result is shown in Table 1.The peeling strength is sufficiently satisfying a bonding strengthbetween the metal core and the insulating substrate required for a metalcore substrate for a circuit board (higher than 1 kN/m).

TABLE 1 Location of the measurement Upper Lower Upper Center Lower UpperCenter Lower side at side at side at at right side at side at at leftside at center center right end end right end left end end left endInitial stage (before the solder heat resistant test) (kN/m) MIN 2.2 2.42.3 2.1 2.2 2.7 2.3 2.4 MAX 2.5 2.4 2.9 2.7 2.5 2.9 2.8 3.0 AVG 2.4 2.42.5 2.6 2.3 2.4 2.5 2.6 After the solder heat resistant test at 260° C.for 60 seconds (kN/m) MIN 2.1 2.2 2.1 2.0 2.0 2.5 2.3 2.2 MAX 2.4 2.52.5 2.4 2.2 2.6 2.5 2.6 AVG 2.3 2.4 2.4 2.3 2.4 2.5 2.4 2.4 Location ofthe measurement Upper edge of the copper plate to be roughened Upperside Upper side Upper side at left end at center at right end CenterLower side Center at left end at center at right end Lower side Lowerside at left end at right end Lower edge of the copper plate to beroughened

Example 2

The anodic treatment is performed on the copper plates with thethicknesses of 400 μm and 200 μm at a solution temperature of 24° C. andan electric current density of 4.5 A/dm² for five minutes. Thereafter,the cathodic treatment is performed at the same solution temperature andan electric current density of 2 A/dm² for approximately five minutes.The processes are defined as one cycle, and the processes are performedtwo cycles, thereby producing the copper plate with the roughenedsurface. A surface of the copper plate with the roughened surface isshown in FIG. 5 (a magnification of 3,000 in SEM). It is found that thegrain size of the protrusion with the fine bump shape on the primarysurface is not larger than 3 μm, and the surface is covered uniformlywith the protrusion with the fine bump shape. A bump with a clustershape is found, and a grain size and a height thereof are not more than10 μm. The surface roughness is measured with a super deep color 3Dshape measurement microscope VK-9510 produced by KEYENCE CORPORATION,and the surface roughness Rz is 11.0 μm.

A commercially available adhesive tape with a width of 10 mm is attachedto the copper plate with the roughened surface, and the pulling off testis performed. As a result thereof, the protrusion with the fine bumpshape is not peeled off, and only an adhesive of the adhesive tape ispeeled off from an interface of the adhesive tape, and the adhesive ofthe adhesive tape remains on the copper plate with the roughenedsurface.

Next, ten sheets of commercially available glass epoxy prepreg FR-4 (aninsulating substrate material) with a thickness of 0.1 mm are laminatedon the copper plate with one roughened side with the thickness of 200μm. They are integrated through pressing and heating under a conditionsimilar to that of a hot pressing of an electrolytic copper foil and theFR-4 prepreg, thereby obtaining a laminated plate of the copper plateand the insulating plate. A sample is cut out from the laminated plate,and a peeling strength test is performed according to JIS-C6471 on anactual sample and a sample after soaking into a molten solder at atemperature of 260° C. for sixty seconds. A result is shown in Table 1.The peeling strength is sufficiently satisfying a bonding strengthbetween the metal core and the insulating substrate required for a metalcore substrate for a circuit board (higher than 1 kN/m).

TABLE 2 Location of the measurement Upper Lower Upper Center Lower UpperCenter Lower side at side at side at at right side at side at at leftside at center center right end end right end left end end left endInitial stage (before the solder heat resistant test) (kN/m) MIN 3.3 3.33.0 3.0 3.2 2.7 3.1 3.1 MAX 3.5 3.6 3.2 3.2 3.5 2.9 3.4 3.5 AVG 3.4 3.43.1 3.1 3.3 2.8 3.2 3.3 After the solder heat resistant test at 260° C.for 60 seconds (kN/m) MIN 3.4 3.2 3.0 3.1 3.0 3.4 3.3 3.4 MAX 3.7 3.53.2 3.4 3.2 3.7 3.7 3.6 AVG 3.5 3.3 3.1 3.3 3.1 3.6 3.5 3.4

Example 3

First of all, there is designed to be performed an anodic treatment foreach of the copper plates that individually have the thickness of 400 μmand 200 μm respectively, with a solution temperature as 32° C., and withan electric current density of 2 A/dm² for approximately five minutesfor each thereof. And then thereafter there is designed to be performeda cathodic treatment for each thereof, with the solution temperature assimilar thereto, with an electric current density of similar thereto,and with an amount of time as similar thereto as well. Moreover, thereis defined the processes as one cycle thereof, and then thereby there isdesigned to be performed the processes as two cycles thereof. Hence,there becomes to be produced a copper plate with a roughened surface.Further, there is shown a state of the surface of the copper plate withthe roughened surface in FIG. 6 (with a multiplying factor of 3000 timesaccording to the SEM). Still further, according to the figure, itbecomes clear that the grain size of the protrusion with the fine bumpshape on the primary surface thereof is not larger than 3 μm, and thatthere becomes to be covered substantially all over the surface thereofuniformly with the protrusion with the fine bump shape thereon. Stillfurther, there becomes able to be recognized thereby that there is apart thereon to become the bump shape as the cluster shape, however,each of the grain size of the part thereon and the height thereof is notmore than 10 μm respectively.

Still further, there is designed to be measured the surface roughnessthereof by making use of the microscope of color 3D for super deep shapemeasurement as the type of VK-9510, that is produced by KEYENCECORPORATION. And then according thereto, the surface roughness thereofas the Rz becomes to be 15.0 μm.

Still further, there is designed for the copper plate with the roughenedsurface to be attached a cellophane tape that is on the market and hasthe width of 10 mm approximately, and then thereafter there is designedthe same to be performed a pulling off test. As a result thereof, thereis not found any peeling off of the protrusion with the fine bump shapethereon at all, but there becomes to be peeled off only the adhesiveagent of the cellophane tape from the interface of the cellophane tape,and then there becomes to be remained the adhesive agent of thecellophane tape on the copper plate with the roughened surface.

Next, there is designed to be laminated a prepreg as similar to thataccording to Example 1 on a copper plate to be roughened one side of thesurfaces thereof with the thickness of 200 μm. And then thereafter thereis designed to be performed the process of pressing with heatingaccording to the condition as similar thereto. Hence, there becomes tobe obtained a laminated plate that is comprised of the copper plate andthe insulating plate. Still further, there is designed to be performedthereafter a peeling strength test regarding the laminated plate assimilar to that according to Example 1. As a result thereof, therebecomes to be obtained the minimum value for all over the plate as 2.1kN/m, the maximum value as 3.1 kN/m, and the mean value as 2.5 kN/m.Still further, regarding the peeling strength after performing theprocess for the solder to be heat resistant, there becomes to beobtained the minimum value for all over the plate as 1.9 kN/m, themaximum value as 2.8 kN/m, and the mean value as 2.4 kN/m. Furthermore,there becomes to be obtained the peeling strength, with sufficientlysatisfying the strength of adhesive bonding for between the metal coreand the insulating substrate, that is required for the metal coresubstrate for the circuit board (as not weaker than 1 kN/m).

Example 4

First of all, there is designed to be performed an anodic treatment foreach of the copper plates that individually have the thickness of 400 μmand 200 μm respectively, with a solution temperature as 22° C., and withan electric current density of 2 A/dm² for approximately five minutesfor each thereof. And then thereafter there is designed to be performeda cathodic treatment for each thereof, with the solution temperature assimilar thereto, with an electric current density of similar thereto,and with an amount of time as similar thereto as well. Moreover, thereis defined the processes as one cycle thereof, and then thereby there isdesigned to be performed the processes as two cycles thereof. Hence,there becomes to be produced a copper plate with a roughened surface.Further, there is shown a state of the surface of the copper plate withthe roughened surface in FIG. 7 (with a multiplying factor of 3000 timesaccording to the SEM). Still further, according to the figure, itbecomes clear that the grain size of the protrusion with the fine bumpshape on the primary surface thereof is not larger than 5 μm, and thatthere becomes to be covered substantially all over the surface thereofuniformly with the protrusion with the fine bump shape thereon. Stillfurther, there becomes able to be recognized thereby that there is apart thereon to become the bump shape as the cluster shape, however,each of the grain size of the part thereon and the height thereof is notmore than 10 μm respectively.

Furthermore, there is designed to be measured the surface roughnessthereof by making use of the microscope of color 3D for super deep shapemeasurement as the type of VK-9510, that is produced by KEYENCECORPORATION. And then according thereto, the surface roughness thereofas the Rz becomes to be 4.0 μm.

Examples 5 to 7

First of all, there is designed to be formed holes as a pluralitythereof individually for the through holes on a copper plate for a corethat has a thickness of between 200 μm and 400 μm by making use of adrill, with diameters of between 3 mm and 5 mm respectively. Moreover,it may be available to be formed the holes by punching out with makinguse of a press machine, because there may become to be required theholes as a significant number thereof that may depend on a specificationof a design for a substrate. Thereafter, there is designed to be formedthe protrusion with the fine bump shape on the surfaces that includesthe inner face of the individual holes by making use of the processesfor producing the protrusion according to the present invention. As aresult thereof, it becomes able to be obtained a copper plate with aroughened surface, that there becomes to be formed uniformly theprotrusion with the fine bump shape not only on the primary surface ofthe copper plate but also including the protrusion at the inner face ofthe individual holes as well, comparing to the plate to be formed bymaking use of the processes for producing the same according to thecomparative example that will be described later. Further, there areshown each of the states of the individual surfaces of the copper platesto be roughened the surfaces thereof in FIG. 8 to FIG. 10 respectively,wherein each of (A) shows the primary surface thereof with a multiplyingfactor of 3000 times according to the SEM respectively, each of (B)shows an inner face of a hole thereon with a multiplying factor of 3000times according to the SEM respectively, and each of (C) shows an edgepart of a hole thereon with a multiplying factor of 125 times accordingto the SEM respectively.

Still further, according to Example 5, it becomes clear that the grainsize of the protrusion with the fine bump shape on the primary surfacethereof is not larger than 3 μm, and that there is a part thereon tobecome the bump shape as the cluster shape, and then that each of thegrain size of the part thereon and the height thereof is not more than10 μm respectively. Still further, it becomes clear that the surfaceroughness thereof as the Rz becomes to be 8.0 μm. Still further, therebecomes to be roughened the inner face of the hole thereon as well, andthen it becomes clear that the height of the protrusion with the bumpshape at the inner face thereof is not higher than 15 μm respectively.

Still further, according to Example 6, it becomes clear that the grainsize of the protrusion with the fine bump shape on the primary surfacethereof is not larger than 3 μm, and that there is a part thereon tobecome the bump shape as the cluster shape, and then that each of thegrain size of the part thereon and the height thereof is not more than10 μm respectively. Still further, it becomes clear that the surfaceroughness thereof as the Rz becomes to be 7.0 μm. Still further, therebecomes to be roughened the inner face of the hole thereon as well, andthen it becomes clear that the height of the protrusion with the bumpshape at the inner face thereof is not higher than 10 μm respectively.

Still further, according to Example 7, it becomes clear that the grainsize of the protrusion with the fine bump shape on the primary surfacethereof is not larger than 3 μm, and that there is a part thereon tobecome the bump shape as the cluster shape, and then that each of thegrain size of the part thereon and the height thereof is not more than10 μm respectively. Still further, it becomes clear that the surfaceroughness thereof as the Rz becomes to be 11.0 μm. Still further, therebecomes to be roughened the inner face of the hole thereon as well, andthen it becomes clear that the height of the protrusion with the bumpshape at the inner face thereof is not higher than 5 μm respectively.

There is designed to be laminated glass epoxy prepreg (a substance foran insulating substrate) as a plurality of sheets onto the copper platewith the roughened surface with the holes that is obtained according tothe processes, and then thereafter there is designed to be integratedthe sheets thereof by pressing with heating. Still further, there isdesigned to be removed a portion of the substance for the insulatingsubstrate at each of the locations for the through holes thereon. Andthen thereafter there is designed to be performed a plating at aroundthe circumference thereof. As a result thereof, it becomes able toobtain a circuit board that there becomes to be formed the through holeswith a diameter of approximately 1 mm, respectively.

As a result of performing a test with applying a high voltage (1000 V)to the finished product, it becomes clear that it becomes able to bemaintained a nonconductivity as sufficiently for between the individualthrough holes and the core, and that it becomes able to function aperformance thereof as excellently. Furthermore, it becomes clear thatthere is not found out any peeling off of the resin or any of cracksthereof at all from the core at around each of the through holes evenafter performing the test for the solder to be heat resistant, and thenthereby that the adherence between the core and the resin is excellentas preferred thereto.

Example 8

Here, there is designed to be produced a copper plate with a roughenedsurface as similar to the processes according to Example 1 to 4, andthen there is designed to be formed thereafter a protrusion with a finebump shape on a primary surface thereof. And then thereafter there isdesigned to be performed a processing for forming a hole for a throughhole on the copper plate. Moreover, there becomes to be obtained acircuit board that is comprised of insulating substrates to belaminated, as similar to the processes according to Example 5.

As a result according to the present example, there is found out atround the circumference of a hole thereon at a period of performing aprocess of drilling by making use of a drill or a punch, such as aportion to be collapsed that is roughened beforehand thereof, a particleof bump shape to be peeled off, an appearance thereof as not to beuniform, or the like. Further, there becomes to be attached an oil forprocessing at a period of punching, and then thereby there becomes to berequired sometimes further process of additional washing. Furthermore,there becomes not to be roughened at each of the inner faces of theindividual holes thereon, and then thereby it becomes to be suspectedthat there may become to be obtained an adherence for between the resinas weaker at each of the inner faces of the individual holes thereon.However, it becomes able to be obtained an adherence at the primarysurface thereof, and then thereby it becomes able to be made usethereof, without finding any problem at all regarding thenonconductivity thereof.

Comparative Example 1

Here, there is designed to be performed an anodic treatment for theabove mentioned copper plate, with a solution temperature as 25° C., andwith an electric current density of 8.5 A/dm² for approximately fiveminutes. And then thereafter there is designed to be performed acathodic treatment, with a solution temperature as similar thereto, withan electric current density of similar thereto, and with an amount oftime as similar thereto as well. Hence, there becomes to be produced acopper plate with a roughened surface. Moreover, in the case thereof, itbecomes able to be roughened a center part of the plate as excellently,however, there becomes to be progressed excessively a dissolution at anend part of the plate due to an electrolysis therein because of theelectric current density as excessively higher. Further, there becomesto be performed the plating excessively as too much thereon, and thenthereby there becomes to be whitened to the utmost. As a result thereof,there becomes to be happened an unevenness for all over the surface ofthe plate, and then thereby it becomes unable to be made use of theplate for a metal core.

Comparative Example 2

Here, there is designed to be performed an anodic treatment for theabove mentioned copper plate, with a solution temperature as 25° C., andwith an electric current density of 0.9 A/dm² for approximately tenminutes. And then thereafter there is designed to be performed acathodic treatment, with a solution temperature as similar thereto, withan electric current density of similar thereto, and with an amount oftime as similar thereto as well. Hence, there becomes to be produced acopper plate with a roughened surface. Moreover, there is shown a stateof the surface of the copper plate with the roughened surface in FIG. 11(with a multiplying factor of 3000 times according to the SEM). Further,in the case thereof, it is found out that there is not progressed to beroughened thereby for all over the surface thereof, and then that it isnot able to be formed sufficiently the protrusion with the fine bumpshape thereon. Furthermore, the surface roughness as the Rz on theprimary surface thereof becomes to be 2.5 μm.

Comparative Example 3

Here, there is designed to be performed an anodic treatment for theabove mentioned copper plate, with a solution temperature as 25° C., andwith an electric current density of 4.5 A/dm² for approximately elevenminutes. And then thereafter there is designed to be performed acathodic treatment, with a solution temperature as similar thereto, withan electric current density of similar thereto, and with an amount oftime as similar thereto as well. Hence, there becomes to be produced acopper plate with a roughened surface. Moreover, in the case thereof, itbecomes able to be roughened a center part of the plate as excellently,however, there becomes to be progressed excessively a dissolution at anend part of the plate and at a hole for a through hole due to anelectrolysis therein. Further, there becomes to be performed the platingexcessively as too much thereon, and then thereby there becomes to bewhitened to the utmost. As a result thereof, there becomes to behappened an unevenness for all over the surface of the plate, and thenthereby it becomes unable to be made use of the plate for a metal core.

Comparative Example 4

Here, there is designed to be performed an anodic treatment for theabove mentioned copper plate, with a solution temperature as 25° C., andwith an electric current density of 4.5 A/dm² for approximately two andhalf minutes. And then thereafter there is designed to be performed acathodic treatment, with a solution temperature as similar thereto, withan electric current density of 2 A/dm², and with an amount of time assimilar thereto as well. Hence, there becomes to be produced a copperplate with a roughened surface. Moreover, there is shown a state of thesurface of the copper plate with the roughened surface in FIG. 12 (witha multiplying factor of 3000 times according to the SEM). Further, inthe case thereof, it is found out that there is not progressed to beroughened thereby for all over the surface thereof, and then that it isnot able to be formed sufficiently the protrusion with the fine bumpshape thereon. Furthermore, the surface roughness as the Rz on theprimary surface thereof becomes to be 2.0 μm.

Comparative Example 5

Here, there is designed to be performed an anodic treatment for theabove mentioned copper plate, with a solution temperature as 35° C., andwith an electric current density of 4.5 A/dm² for approximately fiveminutes. And then thereafter there is designed to be performed acathodic treatment, with a solution temperature as similar thereto, withan electric current density of 1.4 A/dm², and with an amount of time assimilar thereto as well. Hence, there becomes to be produced a copperplate with a roughened surface. Moreover, in the case thereof, therebecomes to be occurred a burning of black color on the surface of thecopper plate due to cuprous oxide. Further, there is designed for thecopper plate with the roughened surface to be attached a cellophane tapethat is on the market and has the width of 10 mm approximately, and thenthereafter there is designed the same to be performed a pulling offtest.

As a result thereof, there becomes to be peeled off the part of theblack color. And then thereby it becomes unable to be made use of theplate for a metal core.

Comparative Example 6

Here, there is designed to be performed an anodic treatment for theabove mentioned copper plate, with a solution temperature as 17° C., andwith an electric current density of 4.5 A/dm² for approximately tenminutes. And then thereafter there is designed to be performed acathodic treatment, with a solution temperature as similar thereto, withan electric current density of similar thereto, and with an amount oftime as similar thereto as well. Hence, there becomes to be produced acopper plate with a roughened surface. Moreover, there is shown a stateof the surface of the copper plate with the roughened surface in FIG. 13(with a multiplying factor of 3000 times according to the SEM). In sucha case, it is found out that there is not progressed to be roughenedthereby for all over the surface thereof, and then that it is not ableto be formed any of the protrusions as the fine bump shape thereon atall. Accordingly, it becomes unable to be made use of the plate for ametal core. Further, the surface roughness as the Rz on the primarysurface thereof becomes to be 1.8 μm.

Comparative Example 7

First of all, there is designed to be formed holes as a pluralitythereof individually for the through holes on a copper plate for a corethat has a thickness of between 200 μm and 400 μm by making use of adrill, with a diameter between 3 mm and 5 mm respectively. And thenthereafter, there is designed to be formed the protrusion with the bumpshape with a diameter as several μm on the surfaces that includes theinner face of the individual holes, by making use of the processes forproducing the protrusion according to the process of the conventionalelectroplating thereof. Moreover, there is shown a state of the surfaceof the copper plate in FIG. 14, wherein (A) shows the primary surfacethereof with a multiplying factor of 3000 times according to the SEM,(B) shows an inner face of a hole thereon with a multiplying factor of500 times according to the SEM, and (C) shows an inner face of a holethereon with a multiplying factor of 125 times according to the SEM.Further, it is found out that the grain size of the protrusion with thefine bump shape on the primary surface thereof is not larger than 5 μm,and that there is a part thereon to become the bump shape as the clustershape, and then that each of the grain size of the part thereon and theheight thereof is not more than 10 μm respectively. Still further, it isfound out that the surface roughness thereof as the Rz becomes to be10.0 μm.

However, according to the copper plate, there becomes to be as notsmaller than 20 μm for a size of the protrusion with the bump shape atthe inner face, that is a difference between a concave thereon and aconvex thereon, comparing to that according to the primary surfacethereof. Still further, even in the case of performing an adjustment ofthe condition for the electroplating thereof, it becomes unable to formany of the protrusion with the bump shape as uniformly thereon withincluding the two of the faces.

There is designed to be made use of the electric current density as alarger amount according to the process of the conventionalelectroplating thereof, and then thereby that there becomes to beconvergent the electric current as the larger amount from the electrodeto each of the inner faces of the individual holes thereon, that havethe surfaces with an area in total as smaller, at the places that eachof the holes passes comparing to other places on the surfaces of thecopper plate that is designed to be faced to the electrode.

Still further, there is designed to be adhered thereafter a substrate ofresin thereon, and then there becomes to be produced a circuit board, assimilar to that according to Example 5. Still further, there is designedto be performed a test with applying a high voltage (1000 V) to theboard. And then as a result thereof, it is found out that there is acase where it is not able to be maintained nonconductivity for betweenthe individual through holes and the core.

Furthermore, according to an analysis, it is found out that in additionto the problem on the adherence of therebetween, there becomes to bepeeled off the protrusion of the copper fine particles due to thepressure of pressing, and then there becomes to be penetrated theprotrusion into the inside of the resin, at the period of the process oflaminating the insulating substrate of resin, and then thereby that itbecomes to be worsened the nonconductivity of therebetween, becausethere is not designed to be sufficiently enough for the distance forinsulation of between the individual holes and the core. That is to say,it becomes clear that there becomes to be happened the problems asmentioned above in the case of producing the copper plate with theroughened surface that the holes are opened thereon, by making use ofthe process of the conventional electroplating thereof.

Thus, according to the above description, it becomes clear thatregarding the copper plate for the metal core that has any of the holesindividually for the through holes in particular, it becomes able toform the protrusion with the fine bump shape on the surface of thecopper plate, by making use of the processes according to the presentinvention, after forming any of the holes on the copper plate, and thenthereby that it becomes able to perform the process of roughening asuniformly for the surface thereof and for the inner face of any of theholes thereon, therefore that it is the optimum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing one embodiment according to the presentinvention, wherein (A) is a plan view, (B) is a cross sectional viewfrom a view point of B-B line in (A), and (C) is a cross sectional viewfrom a view point of C-C line in (B).

FIG. 2 is a view showing one embodiment as another one according to thepresent invention, wherein (A) is a plan view, (B) is a cross sectionalview from a view point of B-B line in (A).

FIG. 3 is a view showing one embodiment as further another one accordingto the present invention, wherein (A) is a plan view, (B) is a crosssectional view from a view point of B-B line in (A).

FIG. 4 is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 1.

FIG. 5 is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 2.

FIG. 6 is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 3.

FIG. 7 is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 4.

FIG. 8A is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 5, wherein there is shown a primary surface thereof.

FIG. 8B is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 5, wherein there is shown an inner face of a hole thereon.

FIG. 8C is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 5, wherein there is shown an edge part of a hole thereon.

FIG. 9A is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 6, wherein there is shown a primary surface thereof.

FIG. 9B is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 6, wherein there is shown an inner face of a hole thereon.

FIG. 9C is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Example 6, wherein there is shown an edge part of a hole thereon.

FIG. 10A is a photo according to a scanning electron microscope showinga state of a surface on a copper plate with a roughened surfaceaccording to Example 7, wherein there is shown a primary surfacethereof.

FIG. 10B is a photo according to a scanning electron microscope showinga state of a surface on a copper plate with a roughened surfaceaccording to Example 7, wherein there is shown an inner face of a holethereon.

FIG. 10C is a photo according to a scanning electron microscope showinga state of a surface on a copper plate with a roughened surfaceaccording to Example 7, wherein there is shown an edge part of a holethereon.

FIG. 11 is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Comparative example 2.

FIG. 12 is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Comparative example 4.

FIG. 13 is a photo according to a scanning electron microscope showing astate of a surface on a copper plate with a roughened surface accordingto Comparative example 6.

FIG. 14A is a photo according to a scanning electron microscope showinga state of a surface on a copper plate with a roughened surfaceaccording to Comparative example 7, wherein there is shown a primarysurface thereof.

FIG. 14B is a photo according to a scanning electron microscope showinga state of a surface on a copper plate with a roughened surfaceaccording to Comparative example 7, wherein there is shown an inner faceof a hole thereon.

FIG. 14C is a photo according to a scanning electron microscope showinga state of a surface on a copper plate with a roughened surfaceaccording to Comparative example 7, wherein there is shown an edge partof a hole thereon.

FIG. 15 is a cross sectional view showing one example of a metal coresubstrate for a circuit board.

FIG. 16 is a photo according to a scanning electron microscope showing astate of a surface on an electrolytic copper foil for a common printedcircuit board.

DESCRIPTION OF THE REFERENCE SYMBOLS

-   -   1 ELECTROLYTIC BATH    -   2 ELECTROPLATING SOLUTION FOR PLATING COPPER    -   3 ELECTRODE    -   3 a POSITIVE ELECTRODE    -   3 c NEGATIVE ELECTRODE    -   4 COPPER PLATE WITH A ROUGHENED SURFACE    -   5 FRAME BODY    -   6 HANGER METAL FITTING    -   7 BUS BAR    -   7 a BUS BAR FOR A POSITIVE ELECTRODE    -   7 c BUS BAR FOR A NEGATIVE ELECTRODE    -   8 INSULATING BAR

What is claimed is:
 1. A rolled copper plate with a roughened surfacehaving a predetermined hole formed at a predetermined position thereof,a thickness of the rolled copper plate being between 100 μm and 500 μm,a surface of the rolled copper plate having a grain size between 0.5 μmand 3.0 μm and a surface roughness Rz between 7 μm and 16 μm, whereinsaid predetermined hole includes a roughened inner surface having aprotrusion with a fine bump shape thereon, and said protrusion with thefine bump shape has a height not higher than 20 μm.
 2. The rolled copperplate according to claim 1, said roller copper plate being producedthrough the steps of: arranging electrodes with a same polarity to faceeach other in an electroplating copper solution; arranging the rolledcopper plate between the electrodes; performing an anodic treatment toform a copper fine particle on both surfaces of the rolled copper platethrough an electrolytic process with the copper plate as a positiveelectrode and the electrodes as a negative electrode; and performing acathodic treatment to fix the copper fine particle to the surfaces ofthe rolled copper plate to form the roughened surface through a copperelectroplating with the copper plate as a negative electrode and theelectrodes as a positive electrode.